With the increasing proliferation of wireless technology, such as Wi-Fi, Bluetooth, and mobile or wireless Internet of things (IoT) devices, more devices or systems incorporate radio frequency (RF) circuitry, such as receivers and/or transmitters. To reduce the cost, size, and bill of materials, and to increase the reliability of such devices or systems, various circuits or functions have been integrated into integrated circuits (ICs). For example, ICs typically include receiver and/or transmitter circuitry. A variety of architectures and circuitry for transmitters and receivers are used. Transmitters send or transmit information via a medium, such as air or free-space, using RF signals. Receivers at another point or location receive the RF signals from the medium, and retrieve the information. Typically, transmitters transmit coded data via RF signals. Receivers receive, decode, demodulate, etc. the RF signals to retrieve the data.
Some wireless communication standards define a preamble for a wireless packet, which is a predefined data pattern that a receiver can use to detect and settle its control loops. The control loops depend on the receiver architecture, and may for example include Automatic Gain Control (AGC), Automatic Frequency Compensation (AFC), and Symbol Clock Recovery (SCR). In some standards and some architectures the AGC loop must settle relatively fast, say within a fraction of the preamble duration. In such standards and architectures it is desirable for the receiver to be capable of fast recovery from RF overload conditions. After the receiver detects the end of the preamble, the receiver is prepared to receive a full packet including payload data. Some receivers use a preamble detector to detect the arrival of a frame. In response to the preamble detector signaling the detection of the preamble, the receiver begins looking for the next portion of the frame. Digital signal processing (DSP) and demodulation (DEMOD) circuitry are typically used to demodulate and generally process the received signals.
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